Two men were critically injured Wednesday in an explosion at a one-story commercial building in Canoga Park where they appear to have been running an illegal narcotics lab, Los Angeles Police Department Sgt. Jeff Collado told KTLA .
The explosion happened at around 11:00 a.m. on the 7000 block of North Alabama Avenue, according to the Los Angeles Fire Department.
The two unidentified men were transported to a nearby hospital in critical condition, according to authorities.
Witnesses told KTLA they saw the door being blown off and two men running out of the building with visible burns on their clothes and bodies.
Fire officials said there was no fire at the site of the explosion when they arrived, but reported possible structural damage to the building.
Aerial video from Sky 5 showed the building's roof partially collapsed. Firefighters were seen with hose lines out near the building. Authorities said it was a precaution.
No smoke or flames were visible at the scene.
The explosion happened in one of the building's units, also damaging two other units, LAFD said.
In an attempt to extract oil from marijuana plants, the men were burning a substance that triggered the explosion, LAPD Lt. Chris Ramirez said a preliminary investigation revealed.
Butane and propane tanks were found in the lab that police described as an "extremely sophisticated operation."
Extracting oil from cannabis typically involves the use of highly-flammable butane, according to a report by Politico that says that at least 10 fires or explosions were reported in the past five years at facilities that extract hash oil in each of the 33 states where marijuana is legal.
Officials sealed off the entire location in the industrial area because of the structural damage caused by the blast.
No further information was immediately available.